net: usb: smsc95xx: Limit packet length to skb->len

[ Upstream commit ff821092cf02a70c2bccd2d19269f01e29aa52cf ]

Packet length retrieved from descriptor may be larger than
the actual socket buffer length. In such case the cloned
skb passed up the network stack will leak kernel memory contents.

Fixes: b9e480c376c5 ("net: Add SMSC LAN9500 USB2.0 10/100 ethernet adapter driver")
Signed-off-by: Szymon Heidrich <szymon.heidrich@gmail.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230316101954.75836-1-szymon.heidrich@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c
index bb4ccbda031abb7e261ddf90ef16f8c679d5cfd6..9a770f7fa5b0294a99a028b041561d3e522085b6 100644 (file)
--- a/drivers/net/usb/smsc95xx.c
+++ b/drivers/net/usb/smsc95xx.c
@@ -1935,6 +1935,12 @@ static int smsc95xx_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
                size = (u16)((header & RX_STS_FL_) >> 16);
                align_count = (4 - ((size + NET_IP_ALIGN) % 4)) % 4;
 
+               if (unlikely(size > skb->len)) {
+                       netif_dbg(dev, rx_err, dev->net,
+                                 "size err header=0x%08x\n", header);
+                       return 0;
+               }
+
                if (unlikely(header & RX_STS_ES_)) {
                        netif_dbg(dev, rx_err, dev->net,
                                  "Error header=0x%08x\n", header);